Yes, but if you look at the list, it's not the reprints I'm talking about...the same card lines are duplicated. So there's a line for Nausea from 7th, then further down, there's another line that it EXACTLY the same.

When you add cards, you are asked if you want to increase the counter of the already existing card (in your collection) or if you want to add another line (even if its from the same edition).What did you do ?

It is more of an intended behaviour of MTG Studio.One might want to have the same card from the same set with the same collector number 2 or more times listed since they might be stored in different binders, used in different decks, or even being signed by the original artist which makes their price different.

One way to easily find duplicates is to export to Excel and or group by Set and Card Name.